Table 2.
Characteristics of study participants, overall and by initiation pathway.
| Characteristica | All girls | Thelarche | Pubarche | Synchronous | P-valueb |
|---|---|---|---|---|---|
| N (%) | N (%) | N (%) | N (%) | ||
|
| |||||
| Total | 3938 (100) | 1482 (100) | 408 (100) | 1631 (100) | |
| Mother's highest education | .03 | ||||
| CSE/none | 583 (15.4) | 212 (14.8) | 43 (10.7) | 243 (15.7) | |
| Vocational | 351 (9.3) | 116 (8.1) | 29 (7.2) | 158 (10.2) | |
| O-level | 1331 (35.2) | 515 (35.9) | 147 (36.7) | 539 (34.8) | |
| A-level | 936 (24.8) | 374 (26.1) | 103 (25.7) | 372 (24.0) | |
| Degree | 579 (15.3) | 217 (15.1) | 79 (19.7) | 236 (15.3) | |
| Mother's prepregnancy BMI | <.0001 | ||||
| <18.5 | 186 (5.2) | 56 (4.1) | 15 (4.0) | 94 (6.4) | |
| 18.5–24.9 | 2671 (75.1) | 1007 (74.4) | 314 (84.2) | 1075 (73.5) | |
| 25.0–29.9 | 516 (14.5) | 208 (15.4) | 37 (9.9) | 217 (14.8) | |
| ≥30.0 | 183 (5.2) | 83 (6.1) | 7 (1.9) | 76 (5.2) | |
| Mother's age at delivery | .02 | ||||
| <20 years | 103 (2.6) | 37 (2.5) | 4 (1.0) | 50 (3.1) | |
| 20–24 years | 620 (15.7) | 240 (16.2) | 43 (10.5) | 252 (15.5) | |
| 25–29 years | 1587 (40.3) | 585 (39.5) | 187 (45.8) | 174 (39.1) | |
| ≥30 years | 1628 (41.3) | 620 (41.8) | 174 (42.7) | 692 (42.4) | |
| Birth order | .01 | ||||
| First born | 1326 (34.6) | 540 (37.1) | 155 (38.8) | 515 (32.6) | |
| Second born | 1277 (33.3) | 485 (33.4) | 137 (34.3) | 531 (33.6) | |
| Third born or later | 1235 (32.2) | 429 (29.5) | 108 (27.0) | 535 (33.8) | |
| Child ethnic background | .0004 | ||||
| White | 572 (96.0) | 1377 (97.6) | 374 (94.4) | 1447 (95.0) | |
| Nonwhite | 148 (4.0) | 34 (2.4) | 22 (5.6) | 77 (5.0) | |
| BMI at age 8 | <.0001 | ||||
| <5th percentile | 69 (2.5) | 20 (1.8) | 12 (3.7) | 29 (2.6) | |
| 5th–85th percentile | 2096 (74.7) | 740 (65.8) | 285 (86.9) | 868 (79.0) | |
| 85th–95th percentile | 348 (12.4) | 182 (16.2) | 23 (7.0) | 121 (11.0) | |
| ≥95th percentile | 293 (10.4) | 183 (16.3) | 8 (2.4) | 81 (7.4) | |
aInformation was missing for some girls, including information on mother's education (n = 158, 4.0%), mother's age at menarche (n = 538, 13.7%), mother's social class (n = 738, 18.7%), mother's prepregnancy BMI (n = 382, 9.7%), sugar in urine at any point during pregnancy (n = 362, 9.2%), breastfeeding (n = 141, 3.6%), girl's birth order (n = 100, 2.5%), girl's birthweight (n = 53, 1.4%), girl's race/ethnicity (n = 218, 5.5%), girl's height at age 8 (n = 1039, 26.4%), and girl's BMI at age 8 (n = 1132, 28.8%).
b P-value is from univariate logistic regression models.